EASY UPS 3S RS-485 common problems

[afecomt]

Dear all

we are facing problems with the EASY UPS 3S when communicating using RS-485

This problems repeats in different countries, with diferent technicians with a common factor: the Easy UPS 3S installation. Sometimes works, sometimes no.

We share a RS-485 bus with sensors  (like temp sensors, schneider, regeltechnik...) with the Easy UPS 3S. when we connect the ups, all the commmunication is lost

When connected directly to PLC, the UPS communicates.

We tried everything: last element resistor..., a direct gnd cable from the panel, only B+B-...

Only solution we have for problematic ups are: isolate the segment with a RS-485 Isolator or if the ups is  installed near the PLC, we cabled a STAR bus, one pair in paralell for the sensors and other only for the UPS and then, sometimes, it works..

Any idea?? Do we need a capacitor in the bus? Any with this problem... 

Installers must use this ups (mandatory by client agreements) and we integrated with our PLC more than 20 the last year, but now we have two in India which are impossible to communicate when more devices are in the bus.

Thanks in advance

[afecomt]

😞

[afecomt]

For anyone interested, 

Schneider support suggested update firmware of the RS-485 card or install a most modern card 

so Schneider is aware that they are selling UPS with a defective card and Schneider technicians, vendors etc are NOT aware about and this cause commissioning costly  problems

[betty4920taylor]

Hello @afecomt,

I understand the frustration that inconsistent RS-485 communication can cause, especially when dealing with critical equipment like the EASY UPS 3S.

Ensure that all devices on the RS-485 bus, including the EASY UPS 3S, have the latest firmware updates. Sometimes, communication issues can be resolved by updating to the latest firmware.
RS-485 is designed for a linear bus topology. If you’re using a star topology, it can cause reflections and impedance mismatches, leading to communication problems. Try to maintain a linear bus as much as possible.
Proper termination and bias resistors are crucial for RS-485 networks. Ensure that the network is terminated at both ends with the correct value of resistors, typically 120 ohms. Also, check if bias resistors are needed to maintain the idle state of the bus.
Use twisted-pair cables designed for RS-485 communication with proper shielding to prevent electromagnetic interference (EMI). The cable should also have a characteristic impedance of 120 ohms.
Ground loops can cause communication issues. Ensure that the system has a good common ground, but avoid multiple grounding points that can create loops.
As you’ve mentioned, using an RS-485 isolator can help in problematic setups. This can prevent ground loop issues and protect against voltage spikes.
Adding a capacitor to the bus is not a standard practice for RS-485 networks. It’s unlikely to solve communication issues and may introduce new problems.
Verify that there are no address conflicts on the bus. Each device should have a unique address, and the master should correctly address each slave device.
Double-check the Modbus settings such as baud rate, parity, stop bits, and data bits. These settings must be consistent across all devices on the network.
If these steps do not resolve the issue, it may be beneficial to reach out to Schneider Electric support for further assistance, as they may have additional insights or firmware updates that could help.

I hope that will help you!!!

Best Regards,

[MorneMeintjes]

Good Morning

Please check on the display if the communication is set for Tuner or not.

If its tuner 485 will not work.

Best Regards

[afecomt]

Hello  MorneMeintjes,

we are going to take in consideration next commissionning of this UPS.

Thanks in advance